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NCT Number: NCT07461129

Electrophysiological Changes in Cases of Different Stages of Keratoconus

Keratoconus is a bilateral and asymmetric disease which results in progressive thinning and steeping of the cornea leading to irregular astigmatism and decreased visual acuity.A typical patient with keratoconus presents in the teens or early twenties with complaints of blurring or distortion in vision and having to change glasses frequently due to changes in refractive error.

Corneal thinning frequently precedes ectasia. In moderate and advance cases, a hemosiderin arc or circle line, known as Fleischer's ring, is frequently seen around the cone base. Vogt's striaes, which are fine vertical lines produced by Descemet's membrane compression, is another characteristic sign. Most patients eventually develop corneal scarring. Munson's sign, a V-shape deformation of the lower eyelid in downward position; Rizzuti's sign, a bright reflection from the nasal area of the limbus when light is directed to the limbus temporal area; and breakages in Descemet's membrane causing acute stromal oedema, known as hydrops, are observed in advanced stages.

Corneal blindness is one of the major causes of reversible blindness, which can be managed with transplantation of a healthy donor cornea. It is the most successful organ transplantation in the human body as cornea is devoid of vasculature, minimizing the risk of graft rejection.

Preoperative clinical evaluation of visual potential after corneal transplantation in the patient with dense corneal opacity remains difficult using only history and biomicroscopic examination. Some studies found that electrophysiologic tests were good predictors of visual prognosis prior to corneal transplantation.

Electrophysiology is an objective functional test of the visual pathway and allows the location of visual dysfunctions to be detected. Full-field electroretinography (ERG) is an established clinical technique used to evoke and record mass responses of the retina to flashes of light. The ISCEV Standard full-field ERGs assess generalized retinal function under dark-adapted (DA) and light-adapted (LA) conditions.The visual evoked potential (VEP) is a cortical response and serves as a functional test of the entire visual pathway from the eye to the visual system of the brain.

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Key information

Conditions

Keratoconus Corneal Diseases Eye Diseases

Age range

18 year–40 year

Sex eligibility

All sexes

Study type

Observational

Primary location

Minia university eye hospital

Minya, Minya Governorate, 61512, Egypt

About this study

Aim of the Study To assess the effect of different stages of keratoconus on electrophysiology test results.

All patients will undergo a comprehensive ocular examination including:

  • Best corrected visual acuity (BCVA).
  • Anterior segment examination using slit lamp bio microscopy.
  • Posterior segment examination using a +78 D condensing lens and peripheral retinal examination by means of binocular indirect ophthalmoscopy (keeler ophthalmoscope).
  • Penatacam examination to define grade of KC and corneal topography.
  • OCT-ONH to assess the function of optic nerve. 6-Electrophysiological tests:

All subjects will be examined using:

  • FVEP: via the assessment of the amplitude &latency of P2 wave
  • PVEP:via the assessment of the amplitude &latency of P100 wave 3- Full field flash ERG: via the assessment of the amplitude & implicit time of a&b waves

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Patients aged from 18 to 40 years with keratoconus of different stages

Exclusion criteria

  • Keratoconus Patients with any prior history of ocular procedures.
  • Patients with dense cataract.
  • Patients with retinal , vitreous problems or uveiitis .
  • Patients with optic nerve pathology
  • History of ocular medications e.g antiglaucoma
  • History of previous ocular surgery

Treatment and study plan

Primary outcomes

  1. Measuring the amplitude of P100 wave in pattern visual evoked potential

    Time frame: 6 months

    Measuring the amplitude of P100 wave of pattern visual evoked potential in mico-voltage in different stages of keratoconus using the (Roland Consult Supercolor Ganzfeld Q450 SC)

  2. Measuring the Latency of P100 wave of pattern evoked potential

    Time frame: 6 months

    Measuring the latency of P100 wave of pattern visual evoked potential in mico-second in different stages of keratoconus using the (Roland Consult Supercolor Ganzfeld Q450 SC)

  3. Measuring the Amplitude of P2 of Flash visual evoked potential

    Time frame: 6 months

    Measuring the amplitude of P2 wave of Flash visual evoked potential in mico-voltage in different stages of keratoconus using the (Roland Consult Supercolor Ganzfeld Q450 SC)

  4. measuring the latency of P2 wave of Flash visual evoked potential

    Time frame: 6 months

    Measuring the latency of P2 wave of Flash visual evoked potential in mico-second in different stages of keratoconus using the (Roland Consult Supercolor Ganzfeld Q450 SC)

  5. Measuring the Amplitude of a wave of Full Field Flash Electroretinography

    Time frame: 6 months

    Measuring the amplitude of a wave of full field flash ERG in mico-voltage in different stages of keratoconus using the (Roland Consult Supercolor Ganzfeld Q450 SC)

  6. measuring the implicit time of a wave of Full Field Flash Electroretinography

    Time frame: 6 months

    Measuring the Implicit time of a wave of full field flash ERG in mico-second in different stages of keratoconus using the (Roland Consult Supercolor Ganzfeld Q450 SC)

  7. Measuring the amplitude of b wave of Full Field Flash Electroretinography

    Time frame: 6 months

    Measuring the amplitude of b wave of full field flash ERG in mico-voltage in different stages of keratoconus using the (Roland Consult Supercolor Ganzfeld Q450 SC)

  8. Measuring the implicit time of b wave of Full Field Flash Electroretinography

    Time frame: 6 months

    Measuring the implicit time of b wave of full field flash ERG in mico-second in different stages of keratoconus using the (Roland Consult Supercolor Ganzfeld Q450 SC)

Sponsors and collaborators

Lead sponsor

Minia University

Other

Registry information

Important dates

Study start
2025
Primary completion
2026
Study completion
2026
First posted
Mar 10, 2026
Registry last updated
Mar 11, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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